1. Field of the Invention
The invention relates generally to methods and apparatus in a printing environment to identify pages for discarding in the printing environment where the identified pages are used exclusively to flush inkjet features of the printing system. More specifically, the invention relates to methods and apparatus for marking a page as a test or flush page to be discarded from a sequence of pages generated by a printing environment.
2. Discussion of Related Art
In ink-based printing system (e.g., inkjet and other ink deposition systems) it is often necessary to clean clogged ink deposition nozzles. As the printing system is producing imprinted images on paper (or other printable media), the frequency and volume of ink usage for each of multiple ink colors may vary. Some ink nozzles for some ink colors may be heavily used over a sequence of printed sheets/images while other nozzles associated with other ink colors may be infrequently used or not used at all. These nozzles with limited use may clog if not maintained by a cleaning procedure.
It is generally known to stop the printing process to permit manual intervention to clear all nozzles of an ink-based printing system. The manual intervention may entail purely manual procedures such as actuating a cleaning request option on the operator panel of the printing system. Or, such manual procedures may entail formatting and printing a page/image that intentionally utilizes all ink nozzles or selected ink nozzles to keep the nozzles clean (by flowing a sufficient volume of ink there through). Such manual intervention gives rise to a need for human intervention to clean the nozzles if not also to format a suitable cleaning page/image and to forward the formatted image to the marking engine of the printing system. This manual intervention can cause a significant delay in the continued processing of the printing system. In high-volume production printing environments, such a delay can be very costly.
It is therefore generally known to provide some automated procedure to flush nozzles of an ink-based printing system without requiring manual intervention and thus without stopping the operation of the printing system to await human intervention. In some known automated techniques, so called “flush lines” are added to an imprinted image while the printing system continues its production printing process. Flush lines are simply rendered graphical images intended merely to cause ink to flow through all (or selected ones) of the nozzles of the ink-based printer. The graphical image so produced by flush lines is not generally intended to represent any information meaningful to a user. Preferably such flush lines are placed on the printable medium (e.g., paper) in an area that may be cut away (e.g., “chipped out”) or may be simply embedded within the printed images preferably in an area that will not render the printed information unusable or unreadable.
However, in a large number of printing applications there may be no area of the page/sheetside image or of the printable medium in which such flush lines may be generated without rendering the intended printed images unusable. For example, the imprinted images may occupy the entire printable surface of the printable medium (e.g., “edge to edge” printing) and/or the imprinted images may simply be of a nature that the flush lines, if integrated within the printable area, would render the printed images unusable for their intended purpose.
It is evident from the above discussion that an ongoing need exists for improved methods and apparatus for performing automated flush procedures for ink-based printing systems.